It’s a medical success story with an unavoidable consequence: Fewer people who suffer severe head injuries are being declared “brain dead” — the major source of organs for transplant.

The findings, published in this week’s issue of the Canadian Medical Association Journal, help explain “stagnant or even declining rates of deceased organ donation,” Canadian researchers say, and mean doctors will need to increasingly look for other sources of organs — including from patients who aren’t formally “neurologically dead.”

The 10-year study of nearly 2,788 brain injured adults in southern Alberta found the proportion who progressed to brain death has fallen dramatically, from eight per cent at the start of the study, in 2002, to four per cent in 2012, and a low of 2.2 per cent in 2010.

The change likely reflects not only a drop in traffic-related deaths and non-fatal crashes, as well as efforts to push helmets for cycling and skiing, but also advances in treating head trauma in every link in the chain, researchers say.

“Patients get their CT scans more quickly, they go to the operating room more quickly,” said lead author Dr. Andreas Kramer, a Calgary critical-care doctor and medical director of the Southern Alberta Organ and Tissue Donation Program.

Less brain death equals less organ donors, frankly

While some patients who don’t progress to brain death still either die or ultimately have “poor outcomes,” there’s much more emphasis today “on protecting the brain in this vulnerable state when it’s injured,” Kramer said.

“This is at a time when the need for organ transplants is at an all-time high.”

Brain death is defined as a complete and irreversible loss of all brain function. Patients can be legally declared dead, even though their heart is still beating and a ventilator is circulating air in and out of their lungs. Normally when the brain is no longer functioning, the person stops breathing. But life support can keep oxygen and blood circulating through the heart, lungs, liver, kidneys and other organs, even though “there is no doubt that that person has died, and there is absolutely zero hope of that individual recovering,” Kramer said.

Brain-dead patients can’t “think, move, feel, sense, want or suffer,” said Dr. Sam Shemie, a professor of pediatrics at McGill University in Montreal and medical director for donation at Canadian Blood Services. “There is no flicker of brain function.”

In those cases, the decision to donate organs is made after the patient is declared brain dead.

Donation after cardiac death, or DCD, is fundamentally different, Kramer said. With cardiac death, “the decision for the patient to be a potential organ donor happens before the patient is actually dead.”

A typical scenario might be, “a patient has a horrible brain injury. Everybody agrees the prognosis is horrible. But they’re not brain dead — their brain hasn’t swollen to this point where they’ve actually progressed to being brain dead,” Kramer said.

If a decision is made with the family to stop life support, the organs can be retrieved five minutes after the heart has stopped beating. All of the organs, save for the heart, can potentially be harvested for transplant.

Doctors aren’t always completely unanimous about things

In 2006, the Canadian Blood Services established medical, legal and ethical consensus guidelines for DCD in Canada.

But there are a number of ethical challenges. “When the decision to consider organ donation is made the patient isn’t dead yet,” Kramer said.

“Doctors aren’t always completely unanimous about things. In most cases, it’s clear that the prognosis is hopeless. But, what if there isn’t complete agreement?”

Another controversy is, how long should doctors have to wait to retrieve the organs? In some U.S. centres such as Pittsburgh, doctors wait two minutes after the heart is stopped before declaring the person dead.

In most countries, including Canada, Australia and the U.K., it’s a minimum of five minutes. In some countries, it’s 10. The longer doctors wait, the more the organs deteriorate.

Another question is, when does the brain stop working in the dying process?

“The question that people have is, is it possible for somebody to suffer after their heart stops? Can they feel anything?” Shemie said.

“The data that we have is that, in fact, in most instances the brain stops working before the heart stops in ICU patients who are dying,” he said.

“So, the answer to the question is no — patients cannot feel or suffer or be awake. They are completely and irreversibly unconscious within seconds after their heart stops beating,” Shemie said.

The other concern is “auto-resuscitation,” where circulation spontaneously resumes. However, Shemie said the phenomenon has never been reported in situations of donation after cardiac death “the way we perform it in Canada.”

In 2006, 32-year-old Sarah Beth Therien, of Ottawa, made medical history when she became the first Canadian organ donor after cardiac death after dying of sudden cardiac death.

Since then, DCD has increasingly been performed in Canada. In 2012, there were 71 adult DCD cases in Canada — 60 in Ontario, 10 in British Columbia and one in Alberta, in Edmonton. Together they resulted in 111 kidney transplants, 20 liver transplants, two pancreas transplants and 12 lung transplants.

In Ontario, donation after cardiac death now accounts for nearly 25 per cent of deceased organ donors, said Dr. Sonny Dhanani, chief medical officer of organ donation for the Trillium Gift of Life Network.

“It’s offering the potential to those families who wouldn’t have been able to donate organs before,” said Dhanani, a pediatric intensive care doctor at the Children’s Hospital of Eastern Ontario in Ottawa.

Shemie said that “in no way should consideration of organ donation” influence the decision to withdraw life support.

“That’s sacrosanct,” he said. “Transplant doctors can have no role in the care of dying patients — they can have no role in the determination of death prior to organ donation,” he said. “That is a legal and moral and strict separation in all our work.”